Logan man... If the fella didn't know Caroll Shelby was an engine tuner... or... even that Caroll SHelby existed... wouldn't it follow that he'd have no idea the Shelby mustang had anything to do with tuning or performance?

these guys are not helpful at all!!!! LOL
But hell ill jump into it... The Price is a big factor and the Heritage is a big factor...
Carrol shelby started working with ford right from the getgo of mustang way back in 65... in 67 they released the GT500 and GT350 (they also did a limited production of GT390s but thats really getting in deep...) Carrol shelby was at the time a famous racing driver and he took to ford for his race cars... Carrol Shelby worked with a number of companies throughout the years and is (some would argue) also responsible for the Dodge Viper as well... His most famous creation many would argue was the Cobra ACR... Basically the smallest sports car body which Shelby promptly dropped a Ford Racing 427into... The cars were basically insane fast... Carrol shelby also had a hand in the ford GT40 lemans race cars which propelled ford to victory in lemans three years in a row slashing back at a Enzo Ferrari team which had previously dominated the event...
Fast forwarding to more recent times Carrol Shelby opened his own shop in his racing retirement... Shelby autos in california... They basically produced replica ACRs and a few other specialty jobs... Officially in 2004 carrol shelby and ford started working together for a special edition of the mustang again appropriatley dubbed the GT500 ... and in 2006 the First GT500 mustang sold at the famous Barret Jackson Auction for charity.
So whats the difference between a GT mustang and a GT500 well for starters the engine is upgraded to a 5.4L DOHC modular engine. The Transmissions are upgraded to T56 six speed trannys. The body pannels get a added flare (also additional body work is present around the front, rear, and skirts of the car). The stance is made more agressive and lower. the cars suspension is upgraded and the brakes grow. power goes from 300hp in the GT to 500 in the GT500. The entire drive train is upgraded and the GT500 comes with bespoke rims and tires. The hood is also changed to a heat extractor style and the rear decklid gets a unique lip spoiler...
Allin all the GT500 is a masterpiece in design and is very reminiscent to the GT500s of the late 60s...
It should also be noted that the GT500 for 2010 will be the first GT500 built entierley by ford and fords SVT (special vehicle team) team in a ford factory... The name is now basically just leased from carrol...
Ford also makes a shelby GT mustang (315hp which is also the 2010 Mustang GT spec) and has in the past 3 years produced the GT500 KR the GT500 supersnake and the GT500 supersnake limited edition... with 540hp 600hp and 750 hp respectively... The supersnake and KR editions are special GT500s that are modified in the Shelby Garage and in my opinion are not 'stock mustangs'
Sorry if i ranted a bit im quite passionate about Carrol's mustangs...
Cheers
-Alex

There are too many Shelby's out there to go into the difference. Make sure that you do your market research before you jump in because there are plenty of Mustangs that have a Shelby badge put on them and there aren't a real Shelby. Due diligence pays off.

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